Lvl 4 skillings what and who can do these?

can we get some info on these lvl 4 skillings all over the map ? who can do them and what level do they need to be
would seem not many know what they are for and why locked.
also any ideas on new aircraft like in planes? figher jets?
how bout naval units? carrier? submarine?
that seems to bout all i got at the moment
thanks for you time
LadyV

It's part of a new tutorial / early-game flow we're trying out to help and better teach new players who are coming onto the Gundar regional maps for the first time. Please feel free to let us know if you spot any issues!